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The AN/VRC-12 and AN/VRC-43 through VRC-49 is a series of combat-proven vehicular radio sets which lend themselves particularly well to applications of tactical deployment and specific operational missions because of their ability to be assembled into various configurations and of being installed on most types of military vehicles; including heavy armour. The equipment provides 920 VHF/FM voice channels in the 30-76 MHz range. It consists of three major units: Receiver-Transmitter RT-246A/VRC with a channel-presetting capability (10 pushbuttons), Manual Receiver-Transmitter RT-524A/VRC with built-in loudspeaker, and Auxiliary Receiver R-442A/VRC.
In addition to the conventional noise-operated squelch, an advanced tone-operated squelch (150 Hz) is provided in this series, thus eliminating "false alarms" or undesired audio output from the receiver when net stations are not called. The tone squelch also ensures reliable retransmission when two receiver-transmitter are used as an automatic relay station in high-density communication centers where off-frequency signals often cause false triggering of the retransmission set-up.
The shown installation is known as a AN/VRC-47 set. It consists of a RT-524A/VRC (receiver/transmitter) and a R-442A/VRC (receiver).
The RT-524A/VRC is a FM Receiver-transmitter, working in the 30-75.95 MHz range with 50 kHz spacing between its 920 channels. Its a manual tuning version of the RT-246A/VRC, has a built-in speaker, and a power output of 8W (low)/35W (high).
Effective range is approx. 10 km (low) and 30 km (high).
The R-442A/VRC is a receiver working in the 30-75.95 MHz range and has 920 channels.
Both radios are powered by 24 V DC.
Some components in the Danish installation are standard (e.g. MT-1029 mounting tray) and some were produced locally (e.g. antenna mount) and have been hard tracking down. The mounting frames and plates placed on the top rear fenders had to be reproduced as no were available.
  Mounting plates, antenna mount and automatic frequency control box being painted

A complete installation consists of following parts:
RT-524A/VRC (1 ea.),
Mounting tray, MT-1029/VRC (1 ea.),
R-442A/VRC (1 ea.),
Mounting tray, MT-1898/VRC (1 ea.),
Mounting frames, (2 ea.),
Mounting plates, (2 ea.),
Antenna mounts, (2 ea.),
Antenna equipment AL-3 consisting of:
-- Automatic frequency control box, AM-30 (1 ea.),
-- Antenna base AB-129/PR (1 ea.),
-- Antenna, AM-31-1 (1 ea.),
Antenna base AB-15/GR (1 ea.),
Mast section, MS-116A, MS-117A, MS-118A (1 ea.),
Adapter, UG-273/U (1 ea.),
  Antenna mount (left) and MT-1029/VRC

Loudspeaker, LS-454/U (1 ea.),
Microphone, M-980DA (1 ea.),
Headset, H-251DA (1 ea.),
Control-box, retransmission, C-2299/VRC (1 ea.),
Mounting-bracket, C-2299/VRC (1 ea.),
Power supply box (1 ea.),
Cable, MK-100/3,6 (1 ea.),
Cable, MK-102/2,5 (1 ea.),
Cable, MK-105/1,0 (1 ea.),
Cable, MK-108/0,8 (2 ea.),
Cable, MK-115/0,8 (1 ea.),
Assorted bolts, washers, etc.
  Right side finished


Frequency: 30.00 to 75.95 MHz.
Channel spacing: 50 kHz.
Number of Channels: 920.
Frequency Stability: Crystal controlled, + 3.5 kHz of nominal frequency.
Mode of Operation: Voice frequency modulated (FM).
Audio Passband: 500 to 3000 Hertz.
X-Mode: Provided.
Squelch: Noise or 150 Hz tone operation.
Temperature Range: -40C to +65C (-40F to +14F).
Operating Voltage: 22 to 30 Vdc.
Size (less mounting):
R-442: 6"H x 5"W x 13"D. (15.2 cm x 12.7 cm x 33 cm).
RT-524: 6"H x 15"W x 13"D. (15.2 cm x 38.1 cm x 33 cm).
RT-246: 6"H x 15"W x 13"D (15.2 cm x 38.1 cm x 33 cm).
Weight (less mounting):
R-442: 18.5 lbs. (8.4 kg).
RT-524: 58 lbs. (26.3 kg).
RT-246: 61 lbs. (27.7 kg).

  Loudspeaker, MT-1898/VRC and antenna mount


Power Output: 35 W minimum @ 25.5 Vdc (high power);  0.5-10 W @ 30.0 ovde (low power).
Frequency Deviation: 8.0 2 kHz nominal; can deviate to 20 kHz.
Speech Compression: Less than 3 dB change in output from 14 dB change in input from nominal audio input of 1.4  mV into 150 Ohms.
Spurious Response: At least 85 dB down within 30.00 to 75.95 MHz range (except at harmonics of IF).
Harmonic Distortion: Less than 10% through transmitter and receiver @ 8.0 kHz deviation over audio passband.
Power Requirement: 10.0A @ 25.5 VDC


(applicable to R-442A/VRC and receiver sections of RT-246A/VRC and RT-524A/VRC)

Sensitivity: 0.5 V for 10 dB (S+N+D)/(N+D) for 8.0 kHz deviation.
Circuit: Superheterodyne single conversion.
Image Rejection: Greater than 85 dB.

  Left side finished

IF Bandwidth: 32 kHz minimum @ 6 dB. 85 kHz maximum @ 60 dB.
Squelch: 150-Hz tone-operated or noise-operated, with RF signal  having 10 dB (S+N+D)/(N+D) ratio.
Limiting: Less than 1 dB change in audio output for RF input from 1 V to 100,000 V.
Distortion: Less than 8% from 500 to 3000 Hertz.
Audio Output: 500 mW into 600-Ohm speaker 150 mW into 600-Ohm headphone.
Volume Control: Adjustable from less than 0.25 mW to 1.0 W maximum.
Power Requirement: 0.75 A @ 26.5 Vdc.
  C-2299/VRC mounted on bracket below the gear shift lever

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